@vincent Thanks for your work, and your answer, both are appreciated! :) Nothing wrong with opinionated, apps that try to appeal to everyone might end up not appealing to anyone.
My main suggestion is that when I tap (or double-tap) one of the tab bar icons, the app should go to the main page of that section. Example: I go into "Mentions", and drill down into a conversation, I would expect another tap on "Mentions" to bring me back to the list of mentions (i.e., to "lift me" out of that convo).
Additionally, if I go into a convo in "Mentions", then head on over to "Timeline", and then return to "Mentions" by tap on its icon, I end up in the previously selected convo again. I'd expect to see the overview of that section, though.